1. Field of the Invention
The present invention relates to an apparatus for press-fitting connectors into a printed board, wherein, by means of press-fitting pins into through-holes formed in a connector, for example, a printed board, a press-fit connector, in which these pins are electrically connected with a pattern formed in the printed board, without the use of solder, is press-fitted into the printed board.
2. Related Art
As is commonly known, in production lines in which parts are automatically mounted on printed boards, there are numerous cases in which apparatuses are provided which press-fit connectors, termed "press-fit connectors", into printed boards. The structural outlines of this type of connector press-fitting apparatus will be explained with reference to FIG. 11. In FIG. 11, stocker 1 stores and maintains a plurality of press-fit connectors 2 (hereinbelow shortened to "connectors") of a single type in a magazine case. Conveyor unit 3 comprises a gripping mechanism 3a, which grips connectors 2 and which is freely movable in a vertical direction, and conveyor mechanism 3b, which conveys this gripping mechanism 3a to the side of insertion unit 4; this conveyor unit 3 conveys connectors 2 which have been removed from stocker 1 to the side of insertion unit 4, and inserts these connectors 2 into insertion unit 4.
Here, the relationship between insertion unit 4 and connector 2 will be explained with reference to FIG. 12. First, connector 2 is provided with a housing 2b having a cross sectional U-shape, and a plurality of pins 2a is vertically provided therein at pre-specified intervals. Pin insertion holes 4a, which correspond to the intervals at which pins 2a are disposed, are provided in insertion unit 4. Pin insertion holes 4a have a tapered opening part, the diameter of the opening part thereof is greater than the diameter of the lead end parts 2a1 of the pins 2a, and is smaller than that of the base end part 2a2. For this reason, the lead end parts 2a1 of pins 2a are inserted into the pin insertion holes 4a, and are thereby aligned. Insertion unit 4 is elastically supported by a shaft 4c which is affixed to an attachment plate 5a, through the medium of a compression coil spring 4d; by means of this, the shock during the installation of a connector 2 is absorbed.
Pin insertion holes 4a communicate with a hollow part 4b which is formed within insertion unit 4, and the pressure within this hollow part 4b is reduced by means of a vacuum pump through the medium of a joint 6. That is to say, when the connector 2 is inserted into this insertion unit 4, the pressure within the hollow part 4b is reduced, and the lead end parts 2a1 of pins 2a are attached by suction within pin insertion holes 4a. The insertion unit 4 which is provided with this type of structure is transported to the press-fitting position by means of the transport mechanism 5 which is shown in FIG. 11. That is to say, as shown in FIG. 11, this transport mechanism 5 moves the insertion unit 4 to a position in opposition to press-fitting head 7 by means of slide rails 5b, which couple the attachment plate 5a described above and the base plate 5c.
Press-fitting head 7 is coupled with a press-fitting unit 8, which is structured so as to be freely vertically movable, and is raised or lowered in accordance with the upwards or downwards motion of this press-fitting unit 8. When the insertion unit 4 is placed at the position in opposition to the press-fitting head 7 by the transport mechanism 5, this press-fitting head 7 comes into contact with the connector 2 within the insertion unit 4, and is attached thereto by suction. The interior of press-fitting head 7 has a reduced pressure by means of a vacuum pump which is not depicted in the Figure, and is attached by suction to connector 2, while on the other hand, when connector 2 is detached, compressed air is introduced into the interior thereof. NC (numerically controlled) movement table 9 is provided above bed 10, and this conducts positioning so that the connector 2, which is in a state of suction attachment, and the connector press-fitting apparatus, which is above the printed board 11, are in agreement, and disposes printed board 11 at a pre-specified position.
In accordance with the above construction, conveyor unit 3 removes a connector 2 from stocker 1, and inserts this into insertion unit 4, and the insertion unit 4 having connector 2 inserted thereinto is placed at a position in opposition to press-fitting head 7 by means of transport mechanism 5. When insertion unit 4 is disposed at a stipulated position in this manner, press-fitting unit 8 descends, and in accordance with this, the press-fitting head 7 comes into contact with connector 2 within insertion unit 4, and is attached thereto by suction. When press-fitting head 7 attaches to connector 2 by means of suction, the press-fitting unit 8 is lifted. Next, transport mechanism 5 returns to its original position, from the position in which insertion unit 4 is in opposition to press-fitting head 7, and in accordance with this, the NC movement table 9 disposes the printed board 11 at the press-fitting position. Here, the press-fitting head 7 again descends in accordance with the movement of press-fitting unit 8, and press-fits the pins of the connector 2, which is in a state of suction attachment, at the press-fitting position on printed board 11. After this, compressed air is introduced into the interior of press-fitting head 7, and connector 2 is detached.
In the conventional connector press-fitting apparatus described above, pin insertion holes 4a which are formed with a tapered shape are provided in insertion unit 4, and by inserting pins 2a in these pin insertion holes 4a, even in cases in which there is positional deviation during the conveyance of connector 2, or in which inclination or bending or the like of the pins 2a occurs, insofar as this is within the largest diameter of the taper, the pins 2a are guided to the opening of the tapered shape, and are inserted into the insertion unit 4.
In the case in which the pins 2a themselves have low rigidity, the inclination or bending or the like is corrected by the insertion thereof into pin insertion holes 4a; however, when the rigidity of the pins 2a is high, when they are removed from the insertion unit 4 by means of the press-fitting head 7 described above, the pins return to the original state thereof. When press-fitting operations are conducted in such a state, even if the printed board 11 is accurately placed at the press-fitting position, the pins 2a will not enter the through-holes formed in printed board 11, and if downward pressing is conducted, there is some danger of causing damage to the printed board 11 or the like. Furthermore, even in the case in which there is no inclination or bending or the like in the pins 2a themselves, if there is a mistake in the position of the printed board 11, the pins 2a will not enter the through-holes of printed board 11 in a like manner, and damage may be caused to the printed board 11 in the same manner.
Furthermore, in the conventional connector press-fitting apparatus described above, connectors 2 which were inserted in an abnormal manner into printed boards 11 are determined to have press-fitting deficiencies and are removed; however, if such connectors 2 are present in large numbers, this presents a problem in that the yield of connectors 2 press-fitted into printed boards 11 worsens.
The cause of the press-fitting deficiencies in the majority of cases is positioning error at the lead end part of the pins 2a as a result of the inclination of the pins 2a of the connector 2. This inclined state of the pins 2a of the connector 2 will be explained with reference to FIGS. 13A-C. FIG. 13A shows the state in which the pins 2a are inserted normally into connector 2, while FIG. 13B shows a state in which the pins are inserted in an inclined manner with respect to the housing 2b. FIG. 13C shows a state in which the pins 2a are inserted perpendicularly with respect to the housing 2b; however, the extent to which the pins 2a enter the housing 2b differs. In FIG. 13A, the upper end part 2a3 of the pins 2a enters the holes 7a of the press-fitting head 7, and these upper end parts 2a3 are held by suction therewithin, so that if in this state the connector 2 is press-fitted into the printed board 11, the base end parts 2a2 of the pins 2a enter the through-holes of the printed board 11, and the press-fitting is complete. In FIG. 13A, the attachment parts 2a4 of the pins 2a of the connector 2 come into contact with the press-fitting surface 7b of the press-fitting head 7 in a perpendicular manner. The states shown in FIGS. 13B and 13C can be considered to be generated during the assembly of the housing 2b and pins 2a of the connector 2; the pins 2a are all inclined in the same direction and to approximately the same extent. In FIGS. 13B and 13C, the inclination of the pins 2a is expressed in an exaggerated manner; however, in the measured values, even when the lead end part 2a1 of the pins 2a is long, having a length of approximately 20 mm, the positional deviation at the lead end is on the level of 0.2-0.5 mm.
Furthermore, in the conventional connector press-fitting apparatus described above, the object of mounting was a single type of connector. However, recently, there are a very large number of cases in which a plurality of types of connectors is installed in one printed board. For this reason, in the case in which a plurality of differing connectors are to be installed in a printed board 11, when the type of connector is altered, the automatic installation operation described above is halted, and each time, it is necessary to replace the press-fitting head 7 and the insertion unit 4 with ones corresponding to the type of connector.
As a result, the portion of the installation operation period with is occupied by the part interchange operation is large, and this tends to lead to a decline in operational efficiency. Moreover, this type of part interchange operation is conducted by human labor, so that this represents a great obstacle to the reduction of power consumption. That is to say, in other words, in conventional connector press-fitting apparatuses, there was a problem in that a plurality of differing types of connectors could not be installed automatically and with a high efficiency.